Summary translation

In the Netherlands agricultural applications of nitrogen and phosphate are subject to restrictions. These rules also apply to organic crop production. To gain insight into the practical implications of these rules for organic growers, we have analyzed the cropping and fertilization schemes of two organic arable farms and three horticultural farms, consulted various experts, and studied relevant literature. Fertilisation with nitrogen and phosphate is limited in Dutch agriculture. This has consequences for organic cultivation practices. In order to get insight in these consequences, crop rotation and fertilisation on two arable farms and three horticultural farms were analysed, experts were consulted an relevant literature studied. Limits for nitrogen do not have substantial effects on organic arable and horticultural farming practices. Limits for phosphate, however, do. On the majority of farms more phosphate is applied than will be possible at the present end date of the change path until 2015. Decrease of phosphate applications while nitrogen applications are kept up to the mark means that soil nurturing fertilisers can be used less. When soil nurturing fertilisers are used a lot, nitrogen supplies can be jammed. Finding the balance between nitrogen supplies on the one hand and care for soil quality on the other hand will become an increasingly important theme on a lot of farms. In this issue two more topics are of importance. The maximum phosphate application is dependant of the phosphate contents of the soil, as expressed in the so-called Pw-number. Is was demonstrated that this Pw-number was generally higher when the farm was managed organically for a longer period of time. When crop rotation and fertilisation are not changed, the situation on farms becomes detrimental more and more. Besides, the organic sector is on its way to 100 % organic fertilisation. Solid manure will become exclusive, while nitrogen-rich organic additional fertilisers are not available and and green compost is not permitted any more. Up to 50 % of the arable farms will have to implement substantial changes in farm management, giving extra attention to crop rotation and fertilisation creates large opportunities for these farms. The situation for horticultural farmers, with only small areas of grass-clover, cereals and green manure, and large areas of nitrogen-demanding crops, is much more difficult. Changes will have to be considerable in order to meet the new rules. This concerns at least 600 hectare. It is clear that on the majority of farms crop rotation and fertilisation will have to get extra attention. The themes that are of importance here are treated in this report: selection of crops (less nitrogen-demanding crops and more soil nurturing crops), growing nitrogen-demanding crops on other farms, usage of fixed driving paths and / or conservation tillage, using green manures more intensively, smarter application of manure and compost, use of separated manure products, usage of cut-and-carry-fertilisers, better choice of additional fertilisers. Agricultural craftsmanship will become more important. Calculations, for example with the dynamic simulation model NDICEA, can be of use here. These themes have not only consequences for the practice but also for research and policy making. The most important themes are treated in this report.